In magnetic disk devices, a technology of suppressing an error caused by repeatable runout (RRO) (hereinafter the error is simply referred to as RRO) to correct a position of a head has been developed. For example, there is a method of measuring the RRO at a plurality of different positions in a radial direction of a disk and correcting the position of the head based on data obtained by interpolating the RRO among a plurality of measured data. In the method of correcting the position of the head, it is necessary to appropriately set the position to measure the RRO.